The current and future research goals are: a) To determine if alpha subunit originated from Beta subunit by proteolytic digestion of complex; b) Comparison of properties of isolated alpha subunit, alpha Beta complex and alpha plus polypeptide fragment generated upon chymotryptic digestion of alpha Beta complex; c) Raise antibodies against isolated alpha and alpha Beta complex; d) Isolate Beta subunit or Beta Beta dimer form; e) Physical separation of DNA polymerase and RNase H activities by limited proteolysis of alpha Beta complex; f) Mode of action of RNase H during reverse transcription and g) Nature of intracellular reverse transcriptase. BIBLIOGRAPHIC REFERENCES: Verma, I.M., H.E. Varmus, and E. Hunter (1976). Characterization of "early" temperature-sensitive mutants of avian sarcoma viruses: Biological properties, thermolability of reverse transcriptase in vitro and synthesis of viral DNA in infected cells. Virology, in press. Lai, M.H., and I.M. Verma. Structural relationship of subunits of reverse transcriptase from avian myeloblastosis virus. Abstract, Cold Spring Harbor Meeting on RNA Tumor Viruses, May, 1976.